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5
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There is always oil on your skin.
Oil helps your skin stay soft. Whenever you touch something the
sweat and oil on your fingers
transfers from your hand to the object that you touch Oil and
sweat are colorless, so the print that you make when you touch
something is not very visable. |
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We call the print you leave behind
when you touch something a LATENT print |
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You can make the print more visible, by allowing a dark dust to
stick to the oils. The police use dusting powder, which is very
light. Put dusting powder on the brush and sprinkle the dust
over the latent print. Blow off the excess dusting powder. Now circle
the print with a crayon. |
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Putting dusting powder on
the latent print |
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After blowing off the excess powder we see the darkened print |
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Using tape we remove the
darkened print from the jar |
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A person may leave a latent print when they touch an object. The
value of the latent print for identification depends on the clearness
of the print and where the print is found. The surface they are
on is also important. Latent prints are often impossible to see
and require the use of
chemicals and powders to make them visible. Latent prints are used to help solve crimes. J. Edgar Hoover |
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EXTRA CREDIT
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You will need to get some supplies.
You will need;
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Put your prints on a glass jar. Show Mom and Dad how to dust and
lift Latent Prints. Have them write you a note telling that they
learned how to dust for prints from you.
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F.B.I. worker dusting a coffee cup for finger prints
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